What would be the best way to alter the viewing distance in an MP level.

For instance, In single player on the Hoth mission, the viewing distance was poor.

Is there any way to do this same effect in MP?

That's done via fog.

Ok then, how do I color it?

And where exactly is the surface texture for the fog?

How do I adjust its intensity?

Fogs are shaders, found in textures/fogs. Look in the Shader manual if you want to see how to make fog yourself.

Example fog shader:

textures/skies/examplefog
{
qer_editorimage textures/fogs/fog1.tga

surfaceparm nodraw
surfaceparm nonsolid
surfaceparm trans
surfaceparm fog

fogparms ( 0.4 0.4 0.4 ) 8192
}

The line surfaceparm fog is what tells the game explicitly that this is a fog.

The line fogparms ( 0.4 0.4 0.4 ) 8192 is what does the real work in the fog shader. The numbers in parentheses are the RGB color values of the fog. The last number is the maximum distance (in game units) that players can see before the fog totally obscures their vision.

You can also map textures onto the surface of the fog to achieve an effect like the surface of water shaders. Look at one of the bespin fogs to see this done.

If you have this fog in your entire level, you can add the key/value distancecull 8192 to your worldspawn and nothing beyond the cutoff distance will be drawn in-game, saving your processor a little. For more on this, see the q3map2 foghull guide (http://www.shaderlab.com/q3map2/manual/foghull_guide.htm).

actually, if you want to change the max veiwing distance because there is hom in the distance, use the worldspawn key distancecull

YOu mean you actually can increase the distance that you see?

yes. if its the default, if you have a distance that is too far, you will get a hom effect, if yu set distancecull farther than that distance, it will be visible